Comment and empty lines not ignored in public key files

[welshjf]

Per sshd(8), on the authorized_keys file format:

Each line of the file contains one key (empty lines and lines starting with a `#' are ignored as comments).

Perhaps one shouldn't assume that gitosis keydir/*.pub files use an identical format; still, it would be less surprising if comments and empty lines were recognized. Currently you can end up with junk like:

command="gitosis-serve test",no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty # test comments, empty lines
command="gitosis-serve test",no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty 
command="gitosis-serve test",no-port-forwarding,no-X11-forwarding,no-agent-forwarding,no-pty ssh-rsa AAA...== test